3D Photoacoustic Imaging

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Figure Caption: Sensitivity of a photoacoustic detection array collected robotically. Rows represent different z-locations within object space. Columns represent different detectors within the array. Each panel represents the sensitivity of a select detector within the xy-plane at a select z-location.
Future Directions

We have spent the last 4 years developing the base technology for 3D photoacoustic imaging. The research has been supported by grants from NSERC, the UWO Academic Development Fund, the Canadian Foundation for Innovation Leading Edge Fund, the Ontario Ministry of Research and Innovation Research Excellence Fund, and through research support and partnership with MultiMagnetics Inc. The developments related to 3D photoacoustic imaging have resulted in one United States provisional patent application. We are currently in the process of testing the technology in a patient trial for use as a diagnostic tool for the detection of breast cancer.

Photoacoustic imaging offers a method to visualize absorption patterns in optically turbid materials, such as tissues of the body, and shows great promise as a biomedical imaging tool (1). Optical contrast is an excellent indicator of health and function (2). Photoacoustic imaging is non-destructive and recent advancements have enabled the visualization of tissue structures at a combination of depth and spatial resolution that is not achievable with other optical methods. The majority of papers to date have reported results on 2D photoacoustic imaging. Researchers in the field are now engaged in extending 2D photoacoustic imaging methodology to 3D and developing real-time imaging capabilities. We have developed real-time 3D photoacoustic imaging technology that can capture 3D images at up to 10 frames per second of a large volume (30 cm3) at a resolution of 0.02 cm3. Real-time imaging capabilities will open up opportunities for many practical applications, including snapshot imaging, high-frame rate 3D imaging (i.e. 4D imaging), and 3D spectral imaging. These advancements will lead to practical methods to follow tissue health and function in real-time and in 3-dimensions.

Researchers
J.J.L. Carson
Imaging Scientist
A. Kornecki
Radiologist
R.Z. Stodilka
Imaging Scientist
F.S. Prato
Imaging Scientist & Imaging Director
Technologies
Optical Imaging
Prototype Facility

Collaborators
M.A. Anastasio
Image Reconstruction
Key Accomplishments

Over the past 4 years, our group at the Lawson Health Research Institute has developed a 3D photoacoustic imaging system for biomedical imaging research. The technology is unique compared to others in that it employs a parallel detection scheme and specialized reconstruction software to permit 3D optical images to be obtained from a single laser pulse [1]. The technology was recently used to perform 4D photoacoustic imaging, where real-time 3D movies of translating point targets and rotating line targets were captured [2]. The work was recently extended to 3D imaging of flow of optical contrast through a tube and hyperspectral imaging of optical contrast. What is believed to be the world’s first single-shot 3D photoacoustic image was captured [1]. What is believed to be the world's first demonstration of 4D photoacoustic imaging, i.e. the capture of a sequence of 3D photoacoustic images, was demonstrated [2]. Advanced calibration methods were developed that utilize automated robotic assessment of the imaging systems [3].

[1] Ephrat, P., Keenliside, L., Seabrook, A., Prato, F.S., & J.J.L. Carson. Three-dimensional photoacoustic imaging by sparse-array detection and iterative image reconstruction. J. Biomed. Opt. 13(5): 054052 (2008) - [PMID: 19021432]

[2] Ephrat, P., Roumeliotis, M., Prato, F.S., & J.J.L. Carson. Four-dimensional photoacoustic imaging of moving targets. Opt. Express 16(26): 21570-21581 (2008) - [PMID: 19104588]

[3] Roumeliotis, M., Ephrat, P., Patrick, J., & J.J.L. Carson. Development and characterization of an omni-directional photoacoustic point source for calibration of a staring 3D photoacoustic imaging system. Opt. Express 17(17): 15228-15238 (2009) - [PMID: 19688001]

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